How this calculation works
Place one straight lateral on each entered row. A straight feeder/header links the first and last row centres and adds your supplied inlet connection length. Apply the order allowance to both tubing subtotals without changing the geometric route or row count.
Lateral length = rows × usable row run; feeder = row-centre span + inlet length; order = route length × (1+allowance)A worked example
For 100 × 60 m, 2 m insets and 10 m row spacing, 6 laterals of 96 m total 576 m. A 50 m header span plus 5 m inlet gives 55 m; a 10% allowance gives 694.1 m combined tubing.
Good to know
One straight lateral per row and a straight feeder route only. No pipe diameters, emitters, fittings, bends, pressure, flow, hydraulic capacity, filtration, water quality or irrigation schedule is designed. No crop spacing is recommended. A zero usable run has no line; no rows means no feeder.
Reference: FAO: drip system components and laterals (opens in a new tab) ↗
Check the land-unit definitions and sources
The standard factors use the international foot and an acre of 43,560 sq ft. Cent means 1/100 acre; gunta means 1/40 acre; the selected Chennai ground means 2,400 sq ft.
The Assam report defines bigha as 14,400 sq ft, katha as 2,880 sq ft and lecha as 144 sq ft. The cited West Bengal court order mentions a 720-sq-ft katha convention. These are explicit presets, not an automatic definition for every record or every place using the same name. Match your record to the stated convention, or use its verified custom factor.
- NIST: exact international-foot and acre factors (opens in a new tab) ↗
- API Setu MDDS: acre/cent and acre/gunta relationships (opens in a new tab) ↗
- Greater Chennai Corporation: one ground is 2,400 sq ft (opens in a new tab) ↗
- Government of Assam AIRBMP framework: section 7.2, page 28 (bigha, katha and lecha) (opens in a new tab) ↗
- Supreme Court order, 7 May 2025: paragraph 2, page 2 (West Bengal katha) (opens in a new tab) ↗
The acre relationships are converted using exact base factors. Rounded or unrelated regional values in a reference table are not substituted for these definitions.
Separate the route length from the order allowance
The example’s six lateral lines each span 96 m after removing a 2 m inset at each end of the 100 m dimension. Their geometric total is 576 m. The first and last row centres are five 10 m intervals apart, so a straight header joining them spans 50 m.
Adding an entered 5 m inlet connection produces 55 m of feeder/header and 631 m of total geometric tubing. A 10% order allowance changes the quantity to 694.1 m. It does not make the actual row route longer or create another lateral.
Use the planting grid tool when the question is the number of plant positions. A row’s planting spacing, emitter arrangement and pipe quantity are separate choices. This tool assumes one straight lateral per entered row without deciding that it is appropriate for a crop.
A length estimate does not size an irrigation system
The FAO reference explains that drip systems include laterals along with other components. This page estimates just a deliberately simple tubing route. It does not choose emitters, diameters, pressure, pumps, filtering, flow, water quality treatment or an operating schedule.
A land elevation profile can make entered rises and falls visible, but linking that profile does not turn this quantity calculator into a hydraulic analysis. Real routes, gradients, bends and operating conditions can require a different design.
With a single usable row, the distance between first and last row centres is zero; the header subtotal then consists only of your inlet connection length. With no positive usable row run or no rows, no lateral or feeder quantity is ordered. The allowance is also zero when the underlying route is zero.
A few questions, answered
Does this round to full coils?
No. It reports length quantities and an entered allowance. Supplier coil sizes and a cutting schedule are separate ordering questions.
Can I use two laterals per row?
This particular model uses one. A two-line or loop arrangement needs an explicit different route model; it is not silently assumed.
Is the inlet length the distance from a well?
It is whatever additional connection length you supply for the modeled route. The tool does not locate or inspect a water source.